Process of treating steel.



PATENTED 00,125, 1904.-

' T. G. SELLEGK.

PROCESS or TREATING STEEL. I APPLIOATIOI FILED AUG. 22, 1903.

K0 MODEL.

I WP.

No. 773,034. PATENTED OCT. 25, 1904.

I T. G. SELLECK. I

PROCESS OF TREATING STEEL.

, APPLICATION FILED AUG. 22, 1903.

N0 MODEL. 2 SHEETS-BREE! 2.

il/ziflesses:

UNITED STATES,

Patented October 25, 1904.

PAT NT OFFICE.

STEEL COMPANY, ILLINOIS.

OF CHICAGO, ILLINOIS, A CORPORATION PROCESS OF TREA'TIINGY STEEL.

SPECIFICATION forming part of Letters Patent No. 773,034,-dated October25, 1904.

Application filed August 22, 1903.

, To all whom it may concern.- d I Be it known that I, THEODORE G.SnLLuoK, a citizen of the United States, residing at Chicago, in thecounty of Cook and State of -Illi-' nois, have invented certainnew anduseful Improvements in Processes of Treating Steel, of

which the following is a specification.

My invention 'relatesto improvements in methods ofproducing soft-centersteel in which a low-carbon or decarbonized steel is packed betweenlayers of a carbonizing compound and is then subjected to a prolongedand a high degree of heat until the surface of the steel has combinedwith the carbon in the surrounding compound to such a depth as may bedesired for any given purpose.

The object of my invention is to facilitate the rapid production of suchsteel and to produce such steel in which the carbonizing process shallbepractically uniform throughout the entire surface of the steel whenthe steel is removedfrom the converting-furnace and in which after finaltreatment the steel shall be free from spots of varying hardness orbrittleness.

These and'such other objects as may hereinafter appear are attainedbythe process hereinafter described, which process may be con venientlypracticed with the apparatus illustrated in the accompanying. drawings,in which- Figure 1 is a sectional view of afurnac'e on the line 1 l ofFig. 2 looking in the direction indicated by the arrows: Fig. 2 is alongitudinal sectional View thereof. Fig.3 is a sectional plan view onthe line 3 3 of Fig. I looking in the direction indicated by the-arrows. Fig. lis a perspective view of a charge of steel and carboniz'ingmixture ready for insertion in one of the boxes of the furnace. Fig. 5is a perspective view of suchcharge with the envelop partly removed, andFig. 6

is a cross-sectional view of such package and its contents.

Like letters of reference indicate the same parts in the several figuresof. the drawings. In the form of furnace shown the rear wall of thefurnaceA is provided with an oil- Serial No. 170,388- (No specimens.)

burner opening B, communicating with 1 the combustion-chamber C.Arranged at the back G, which support arches H, said arches constitutingthe tops of the flues F and the bottoms of the boxes 1. At their forwardend said flues communicate with another transverse flue J, whichcommunicates with vertical flues K, which lead over baffle-walls L intolongitudinal fluesM, arranged between the boxes,

the space over the boxes and in free communication with saidlongitudinal flues consti- Which flues 0 lead into thev chimneys P fortuting a chamber or horizontal flue N, from the escape of the wasteproduct of combustion. It will thus be seen that a jetof flame enteringthe combustion-chamber is deflected by the deflecting-wall and is brokenup into a sheet of flame, which passes forwardly through thelongitudinal flues upwardly and back over and between the boxes, thuskeeping the boxes at all times surrounded by a mass of live flame, whichwill insure a constant and substantially uniform high degree of heat inall parts of said boxes. Y Figs. 4:, 5, and 6 show a convenient formofpacking the charges of steel for insertion in the boxes. Q is athin'wooden box roughly made, within which is laid a sheet of paper R,upon which is then laid a layer of carbonaceous compound S. Upon thiscompound is laid a layer of the pieces of steel T which are to beconverted. "The steel is then covered with another layer of thecarbonaceous compound, other layers of steel are add ed, and so on untilthe package is filled, when the free edges of the paper are foldedoverthe layers of steel and carbonaceous compound and the passage isclosed by loosely nailing on strips U.

4 It is understood in this art that for the purpose of converting thesoft steel to soft-center steel it is necessary that the pieces of steelshall be packed in and surrounded by layers of a highly-carbonaceouscompound and that these layers of carbon shall be held in placesurrounding the steel during the converting process. It will thus beseen that in the manner described the pieces of steel to be convertedare effectively surrounded with the carbonaceous compound and thecompound is effectively held in place in a very simple and inexpensivemanner, the packages thus formed being of such a size as will be readilyinserted within one of the boxes I, so as to be thoroughly inclosedtherein. Obviously the carbon compound can be held in place as readilyby other suitably-removable means, which may be used quite as well asthe paper and wood shown and described.

It is the common practice in this art to pack the steel to be convertedor the articles to be ease-hardened into receptacles in the furnacebefore the furnace is heated, to then raise the furnace to the requiredtemperature, which requires about a week of continuous heating, tomaintain the furnace at such high temperature for the required length oftime, to then allow the furnace to cool off, and to then remove thesteel or steel articles from the compartments in the furnace. Theobjection to this method is the loss of time in heating and cooling thefurnace and the fact that as the steel is inaccessible while the furnaceis at its highest temperature the steel cannot be examined and testedbefore removing the entire charge from the furnace and the extent towhich the process of conversion is gone cannot be known with anycertainty. It is also a known practice to pack the steel or steelarticles in metallic cases, which are inserted in compartments in thefurnace; but this practice is also objectionable for the furtherreasons, first, that the metallic packages must be heated to a highdegree before the requisite degree of heat reaches the steel packedtherein, and, second, that this heating tends to destroy the packagesand to thereby increase the cost of conversion to a prohibitive figure.

In the practice of my invention I preferaby use a furnace, such as thatshown in the drawings, in which the boxes or compartments for removingthe steel may be surrounded on all sides by live flame and which, owingto the fact that the boxes open at their forward ends through the frontwall of the furnace, which open ends may be readily sealed and unsealed,may be charged and discharged without cooling the furnace. Thisconstruction enables me to keep the furnace at all times at a convertingtemperature, to examine and test the steel from time to time, to rapidlydischarge the boxes of the furnace without reducing the temperature ofthe furnace, and to immediately recharge the same while the furnace isat the same high temperature, thereby causing the converting process tobegin at once.

In preparing the charges of steel 1 pack the same between layers ofcarbonizing compound in packages which may be quickly removed after thecharges have been inserted in the boxes of thefurnace. This removal ofthe packages may be accomplished either by confining the charges bycombustible means-such as wood, rope, or any other combustible packageorby inclosing the charges in packages which may be mechanicallywithdrawn, such as metallic sheets or en velops or the like. In practiceI prefer packing the charges between layers of carbonizing compound inthin wooden boxes. These boxes may be very cheaply and hastily made and,if desired, may be lined with paper which surrounds the charges toconfine the carbonizing compound,

which might otherwise sift through the cracks in the boxes if the boxesare not mad 0 tight. .I next insert the boxes containing the charges inthe boxes of the convertirig-furnace, the wooden or like boxescontaining the charges being pushed sufficiently far back into thebrickwork boxes of the furnace to be substantially unaffected by thecooling which occurs immediately adjacent to the open ends of thebrickwork boxes. hen wooden or other combustible packages are used toinclose the charges, the intense heat of the furnace quickly destroysthem and the charges are immediately subjected to a convertingtemperature. It is of course understood that immediately after thecharges are inserted in the boxes of the furnace the open ends of thefurnace-boxes are sealed in any suitable manner to prevent both thecooling and the active combustion which would result from thefree accessof air thereto. hen there is reason to believe that the convertingprocess has continued for a sufficiently long period, the outer ends ofthe furnace-boxes may be opened and test-bars removed and tested.Whenever the test-bars show that the hardening or conversion of thesteel has proceeded to a sufiicicnt extent, the furnace boxes aredischarged. The converted steel is next allowed to cool and is thenannealed in an annealing-furnace. I have found, however, that where thesteel is simply allowed to air cool and is then annealed there willfrequently be found irregularly-distributed spots of irregular sizewhich crack under the action of the shears or other tools, showing thatthese spots have been unduly hardened. Such brittle spots constitutedefects which are fatal to the value of the metal for most purposes.Such defects appear to be due to the fact that when the charges areremoved from the furnace particles of the carbonizing material adhere tothe metal in more or less irregular spots and the converting action atsuch spots does not immediately cease. In any event 1 have found that byplunging the metal into water immediately as it is discharged from theconverting ovens or boxes, then allowing it to cool, and then annealingit in an annealing-furnace I avoid these faulty spots and producesoftcenter steel of uniform quality throughout.

In using the term removable package in my specification and'claims Irefer to any package which may be removed from around the'charges afterthey have been inserted in charge contained therein While the charge isin the-converting zone.

2. A process of converting steel, Which comprises surroundingloW-carbonsteel With acarbonizing compound, inclosing the charge, so formed,Within a removable package, conveying said package into a convertingzone,

and then removing the package by combustion from'around the chargecontained therein.

THEODORE G. SELLEOK.

Witnesses:

GEORGE O. GUNDERSON, O. R. BARNETT.

